Black area around my sniper scope starts recoloring?

Hi,
I'm not sure if this is the right place to ask for help, but I'll ask it anyways.
for the last few days I've been dealing with the problem that whenever I zoom in with the sniper, the black area around the crosshair starts coloring a very bright white, or leaves a ''print'' of what was behind it in blue/blackish.
Now I know this has something to do with the texture modding I've been doing, but I'm not sure where I made the mistake.

I have only made weapon skins and custom scopes(the custom scopes are not the problem, since I used them for a long time without a problem)